My ISM re-power is working great now that I have most of the fine tuning done. The one area I'm not totally happy about is the cooling system. I used the original blower driven off the crankshaft. I know by how cool the motor runs that I have a lot of excess cooling capacity and am wasting horsepower/diesel by using the system as it is now.

I'm thinking about using an electric fan to pull air through my radiators/CAC on my ISM re-power instead. Do you guys have any good sources I can use to get a couple (2) electric fans? Considering how cool my installation runs I'm thinking I could be happier with an electric setup than always pulling air through and on to the engine.

Alternatively, maybe a hydraulic motor in place of the blower box would work if I could turn the motor on and off with a relay. Any ideas on a reasonable double shafted/taper shafted hydraulic motor? I would prefer a multiple speed motor controller if at all possible.

You can reduce the HP required by the fan by reducing the amount of air it moves.You can do this by putting a smaller pulley on the crank or a larger pulley on the fan.

Cheaper still is to damper the inlet or outlet of the fan. You could do this by putting one of those cold weather covers on your radiator like the big trucks do. Easy to adjust for current conditions too.

Usually, the electric fans that will last in this type of application are quite expensive & electric power hogs that may require a larger alternator.

Glad things are working out

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Hi Brian. You must not recall the "famous" thread on BNO that involved Two Dogs a few years ago. That was the thread of all threads. Basic conclusion is that electric fans will not do the job.

I have a photo of an MCI where the person appears to have installed heating fan motors from a bus (motors must be several HP and maybe 12-14 inches in diameter). Did not hear how that worked.

On my Eagle, I have an air clutch fan hub drivng a large plastic type truck fan (can't use the heavy Eagle fan as I am sure it would tear up the clutch with the big inertia). I tried hooking it up to the Series 60 control system, but for some reason it does not trigger the fan. I now have it hooked up to a switch on the dash (controls the Series 60 air valve).

I find that the fan must be on most of the time. I sometimes turn it off when it is cold outside (less than 40), but even there it will start to get hot on big hills.

When you consider that the fan draws maybe 15 HP (guess) and the bus takes maybe 200 HP at 70 (wild axx guess), I don't think you would ever see it in fuel mileage.

Cheaper still is to damper the inlet or outlet of the fan. You could do this by putting one of those cold weather covers on your radiator like the big trucks do. Easy to adjust for current conditions too.

Glad things are working out

The MCI blower draws air in thru a round inlet and then dumps it out a square opening down on to the engine. I don't understand how vacuum and air flow affect horse power so forgive me if this question is stupid. If I were to put a restrictor plate over the inlet to reduce the opening size I would reduce the amount of air flow. How or would this reduce the hp required to run the fan? Wouldn't the vacuum effect cause more HP to be used instead of less?

The MCI blower draws air in thru a round inlet and then dumps it out a square opening down on to the engine. I don't understand how vacuum and air flow affect horse power so forgive me if this question is stupid. If I were to put a restrictor plate over the inlet to reduce the opening size I would reduce the amount of air flow. How or would this reduce the hp required to run the fan? Wouldn't the vacuum effect cause more HP to be used instead of less?

Brian,

Find a small squirrel cage / centrifugal blower. Run it with inlets and outlets open. Then, slightly cover the inlet. You'll hear the motor speed up. That's 'cause it's moving less air. Less air being moved = less power needed. I like the idea of a damper or plate that could be used to partially cover the air inlet on the blower.

The MCI blower draws air in thru a round inlet and then dumps it out a square opening down on to the engine. I don't understand how vacuum and air flow affect horse power so forgive me if this question is stupid. If I were to put a restrictor plate over the inlet to reduce the opening size I would reduce the amount of air flow. How or would this reduce the hp required to run the fan? Wouldn't the vacuum effect cause more HP to be used instead of less?

Brian, the required HP is a result of mass of fluid moved & pressure differential.

Most of our intuition comes from pumping incompressible fluids. If you were pumping oil & blocked off the outlet, yes HP would increase because you are building pressure.

However, with a centrifugal fan & Air (which is highly compressible) , our intuition fails us.

Sorry I can't explain it better.

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So, given this thread I'm starting to lean more towards an inlet restriction that is controllable/variable. I'll have to give this some thought on how to make it variable, reliable, and easy to construct/maintain. Any ideas?

Look at how the big trucks cover their radiators. Maybe you can get a trim shop to sew you some external covers that snap on (like pickup bed covers). Maybe have a couple different sizes made for differing conditions.

Maybe you make some metal covers - Hey, Chaz may be ready to work with some metal for a change after what he's been working on lately.

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Hi Brian,I hate to put a damper (pun intended) on your solution of restricting the air flow through your radiators. But, if you restrict the air flow through the radiators you will also be reducing the air flow through your intercoolers, thus taking less heat out of your combustion air. What effect will that have on your engine efficiency? Perhaps none, but it may be worth some thought. Why aren't your thermostat(s) keeping your engine at the correct temperature? It seems to me that if your thermostat(s) are doing their job you would have proper operating temperature.Another thought I have is, would you have enough cooling with just one radiator? Or, if not, would it work to reduce the coolant flow instead of the air flow through the radiators? Maybe a controlable variable volume valve would work. Ah, the fun continues.Good luck, Sam 4106